Reduction of metals to a powder



A. W. FERGUSON REDUCTION OF METALS TO A POWDER June 13, 1944.

original Filed Jan. 28, 195e '.EMM

vENToR ATTORNEYS UNI-TED' STATES PATENT OFFICE 22,494 REDUCTION l' METALS T0 A IWDEB t Allan W. Ferguson. East Aurora, Y., assignor to Oxides, Inc., Buffalo, N. Y.

Original No. 2,209,964, dated August 6, 1940, Serial No. 187,424, January 28, 1938. Application for reissue January 31, 1944, Serial No. 520.493

17 Claims. (Cl. 83-9l) Another object of this invention is to providev an improved method of reducing metals, and particularly those of low fusion point, such as lead, to a very finely divided powder of which 90% or more so obtained will easily pass through a 200 mesh screen, with which one may obtain a metal in the form of a powder, the particle surfaces of which will have a minimum coating of oxide thereon, and the ilneness of which in substantial or commercial quantities obtainable at prices making their ready sale possible, is greater than has been available by other methods.

Another object of the invention is to provide an improved apparatus by which low fusion point metals, such as lead, may be reduced to a vfinely divided powder of exceptional iineness, with which the proportion of the metal reduced to such iineness will be a maximum and greater than heretofore has been possible, with which a remarkable uniformity in the degree of such neness of the powdered metal may be obtained, which will be compact, efilcient and inexpensive in construction, and with which the cost of operation will be relatively low.

Another object of the invention is to provide improved methods and apparatus for producing a powdered metal, of relatively low fusion temperature, of such iineness that subsequent milling or reduction-in size of the particles will be unnecessary, and which in the case of powdered lead, can be easily converted into oxides of different kinds with a minimum residue or proportion of metal or unoxidized lead in the particles.

Various other objects and advantages will appear from the following description of two examples of the invention, and the novel features will be pointed out hereinafter in connection with the appended claims.

In the accompanying drawing:

Fig. 1 is an elevation of apparatus constructed in accordance with this invention and particularly useful for the practice of the method of this invention and illustrating one example thereof ;l

Fig. 2 is a longitudinal sectional elevation through the atomizing nozzle forming a part thereof;

Fig. 3 is a longitudinal sectional elevation through the discharge end of said nozzle, on a somewhat larger scale;

Fig. 4 is a sectional elevation through the discharge end of the nozzle, the section being taken substantially along the line 4-4 of Fig. 2; and

Fig. 5 is an elevation, partly in section, of the discharge end of another nozzle representing a modification of the invention in which but a single stream of the molten metal is mixed with the stream of hot gas.

In the example of the invention illustrated in Figs. l to 4 inclusive, the apparatus illustrated includes a pot I0 of any suitable material which will withstand the temperature to which the lead or other metal must be raised. This pot is suspended by a ange II at its upper end from a suitable enclosure I2 having insulation I3 encircling it. A suitable burner I4 or other suitable heater is placed in the bottom of the cabinet beneath the pot, and the enclosure I2 is provided at its lower end with openings I5 for the admission of air to support combustion of the gas discharged by the burner I4. The waste gases of combustion 0 from the enclosure I2 are removed in any suitable manner such as through a pipe I6 leading from adjacent the upper part of the enclosure I2 to a. stack I1. The pot II). is closed at its upper open end by a plate I8 which is removably clamped to the open face of the pot in any suitable manner such as by means of screws I9 passing through the plate I8 into the iiange II.

A pipe passes through the plate IB and depends therefrom into the pot III to a point adjacent the bottom of the pot, and after passing upwardly through the plate IB it enters a casing 2l forming part of the spraying or atomizing device. The casing 2i is L-shaped in general form, and the pipe 2li enters the short arm of the L and then bends and extends along the long arm of the L which is preferably in a horizontal position, as shown in Fig. 1. Short fins 20a secured on the pipe 2li within the casing 2i engage with the casing 2i and space the pipe 20 from the wall 50 ofcasing 2|. These fins run in directions lengthwise of the pipe and do not offer material resistance to gas ilow through casing 2|. The pipe 20 is of cours anchored and sealed firmly in the plate I8, and the lower end of the casing 2i where the pipe 2l enters it is of course also sealed and connected to the plate I8 so as to be a unit therewith. The passage 22 in the casing 2| through which the passage 2|) extends is provided at the free end of the long arm of the L of the casing 2| with a tapered or progressively reduced zone 23. which terminates in an orifice into which a sleeve 2l is mounted, preferably for limited adjustment in a direction into and out of the casing 2|.

The sleeve 24, for example, may be threaded into the opening in the end of casing 2| and locked in different adjusted positions therein in any suitable manner, such as by a lock nut 25 and a lock washer 28. The tapered portion or zone 23 of the casing 2| thus acts as aprogressively constricting or converging portion o`f the passage 22 which leads to the opening in the sleeve 2l.'

as shown clearly in Fig. 2. 'I'he outer end of the sleeve 2| is constricted to a spraying orifice 21, and the outer end zone of the passage 2B of the sleeve 24 preferably converges or tapers somewhat gradually or progressively towards the restricted orifice 21.

The lportion of ypipe 20 which extends along the horizontal arm or leg of the casing 2| hasa reduced extension or terminal end 29, which projects into the passage 28 oi' the sleeve 2l to a substantial extent but which terminates a substantial distance in advance or in front of the spraying orifice 21 in the sleeve 2l. The passage 30 of the pipe 2li merges into the smaller passage 3| of the extension 29 through a tapered or progressively changing zone 32, so that as the metal from the pot i leaves through the pipe 2l, its travel will be speeded up by the tapered zone 32 as it enters the passage 3| of the extension 29. This ,passage 3| at its discharge end is split or divided into a plurality of separate passages 33 and 3l of substantial length which extend to the discharge end of the extension 29 and there terminate in countersunk or flared ends 35 and 26 respectively. The extension 2! is, of course, substantially smaller than the 'passage 28 in the sleeve 2l, and it is so positioned in the sleeve 2l and the passages 33 and 3l are so spaced from one another that the longitudinal axes of the passages 33 and 34 will be approximately in line with the periphery of the discharge orifice 21 of the sleeve 24. The conduits 33 and 24 are thus eccentrically mounted with respect to orifice 21.r

Any number of passages 33 and Il may be employed in the extension 29, but all of them preferably have the diverging or daring discharge ends directed towards the periphery of the orifice 21 so that the streams of molten metal discharged from passages I3 and 3l will be oi' the spreading pencil type as they leave the extension 29 and enter the passage 2l. The length of passages 33 and 3l may vary to some extent. but they are preferably long enough so that the liquid metal passing therethrough will be discharged into passage 2B as slightly spreading pencil streams. If the passages 33 and 2l are too long and of too small diameters. they oil'er undesirable frictional resistance to the passage of the molten metal therethrough.

The discharge end of the sleeve 2l is preferably inserted through a window or opening 31 which is open to the atmosphere in a spray chamber 38 of any suitable design or character, and the atomized metal settles out of the atomizing gas in this chamber. A pipe 39 is connected to the casing 2|, preferably approximately in line with the horizontal section thereof, so as to supply a gaseous atomizing medium to the passage f5 22 of the casing 2|. The gaseous medium for disintegrating the molten metal may be air or any other suitable gas readily available, and where the metal is to be discharged without oxidation or other chemical change, the gas selected should preferably be one which is inert to harmful or appreciable chemical reaction with the metal under the atomizing conditions.

In the atomizing of molten lead, for example, the tomizing medium is' conveniently air under substantial pressure, and this gaseous medium or air should preferably be heated to a temperature substantially in excess oi' the fusion point of the metal being atomized. The atomizing is so rapid once the air and lead streams meet that' no ma.- terial oxidation occurs through such contact. In the illustrated example of the invention, the pipe 39 which supplies this gaseous medium, such as air, to the atomizing device through the pipe is connected to one end of `a lpipe coil 4D provided in a heater cabinet 4| which is supplied with heat through a suitable gas burner 42 or in any other suitable manner. 'I'he gases of combustion from the burner I2 may also be conheater cabinet 4| may be of the insulated type.

vand the coil Il may be a spiral or any other type of coil so long as it provides the necessary total length to obtain adequate exposure of the compressed gas to the action of the heat. A pipe 4l connects the other end of the coil 40 to a pipe M leading to a source l5 of compressed gas such as compressed air.

In the drawing I have illustrated conventionally a reservoir i'or air with a, compressor and motor mounted thereon, but it will be understood that any other source of compressed air or other gas may be employed. For maximum eiilciency of the apparatus and of the method, the gas under pressure should have not only a substantial pressure, but also a uniform pressure throughout operation. Other means, such as accumulators are well known for providing sustained pressures of any desired amount; and therefore it will be understood that the source `l5 is illustrated only by way of example.l A valve 4l is included in the .pipe Il for regulating the ilow of gas or air through the pipe coil I in the heater and thence to the 4spray casing 2l, and a pressure gauge l1 connected to the pipe l! indicates at all times the pressure of the gas actually delivered to the spray casing 2|.

A suitable temperature indicating device is provided in the pipe l! for indicating the temperature of the air or gas delivered to the spray casing 2|. For example, a pyrometer IB may be inserted in the pipe 3l as it leaves the heater cabinet Il, and connected by wires Il to a temperature indicator Il. A branch pipe 5| is connected to the pipe Il before it reaches the valve 4I and this pipe contains a valve 52 therein by which the flow of gas through this branch pipe may be selectively regulated for a purpose which will appear presently. The pipe 5| is connected to the interior of the pot III, such as by extending it downwardly through the plate l where it opens into the upper end of the pot Il. Thus when the valve I2 is open, a compressed gas such as air may be forced into the vupper end of the pot Il, and the gas pressure therein will force the molten metal pipe 2l.

A pet cock or bleeder valve I3 may be connected to the :pipe Il between the valve l2 and the pot Il, so that when the valve I2 is shut oil'.

our of the pot through thepressureintbepot Ilmaybcrestoredto atmosphere; It also is a means for escape ot air lromthepotwhilethepotisbeingnlledwith further molten metal in any suitable manner. Whilethemetalsuchasleadmaybefusedin the pot Il, thisiusim mayadvantageously be carried on outside of the pot Il. and then admitted while in a molten condition to the pot Il. For this purpose a nlling pipe M is provided on the plate Il. so as to open therethrough, and this pipe Il is normally closed such as by a cap Il. When the pot il is to be iillled with molten lead. the cap ilmay be removed from the pipe M. A filling pipe Il is then connected to the pipe I and the molten metal then delivered by gravity or under pressure from any melting pot (not shown) through the pipes Il and Il to the pot III. During this nlling, the air in the pot which is displaced by the entering molten metal may escape through the pipe Il and bleeder valve Il.

After the pot Il has been refilled, the pipe l.

is disconnected and the cap il replaced, whereupon the apparatus is again ready for a spraying operation as soon as the metal in the Dot Il has been brought to the desired temperature. In order to indicate the temperature of the molten metal in the pot at any time a suitable temperature indicating device. such as a pyrometer 51, may be mounted on the plate Il so as to depend ,into the molten metal in the pot, and this depending portion of the pyrometer is connected in any suitable manner. such as by wires Il to theI temperature indicating device 59, as

usual in pyrometers.

In the operation of the apparatus illustrated in Figs. 1 to 4, the compressed air or gas is supplied from a source l! and pipes 4I, I3 and il to the heater cabinet ll and to the upper end 4oi' the pot Il under the control of the valves 46 and 52. 'Ihe air in the pipe or coil l0' Within the cabinet ll is heated to the desired temperature which will be indicated by the indicator 50 as soon as there is any movement of air through the coil Il, and this heated air is delivered then to the spray casing 2| where it is conducted as a tubular stream through the passage 22 thereof to the passage 2l of the sleeve Il. With the plate Il sealed on the top of the pot Il. and after the metal in the pot Il has been raised to the desired temperature above its fusion point, the opening of valve 52 will place a gaseous pressure on the interior of the pot Il and this pressure will then force the molten metal out of the pot Il through the pipe and discharge it into the passage 28 of the sleeve 24 as a plurality of small streams from the passages 33 and ll, which because of the flared discharge ends Il and 3l will be of the expanding pencil or stream type.

The valve ll is usually first opened to cause the air to pass through the heater cabinet Il and thence through the spray casing 2l and sleeve 24. from which it is discharged through the constricted orifice 21. This heated air heats 'the casing 2| andthe sleeve 24, as well as the portion of pipe 2l within casing 2i. and the extension!! above the fusion point of the metal in the pot Il, and while the air is thus passing the valve l2 may be opened to admit air pres-k sure to the interior of the pot Il and force the molten metal from the A.bottom of the not out through the pipe 2l. 'Ihis causes the discharge of a plurality of pencil like streams into the passage 2l directly towards the periphery of Aairstreams the orifice I1. Thus the streams of molten metal are discharged into the stream of hot compressed gasor airinthepassage 2I.wheretheleadand intermix. The gas or air passing under hiah pressure into e 2i grabs. so to speak. lthe Yexpanding pencils or streams of molten metal and tears them into small particles or globules, and the mixture is then forced under highzcampressil on and pressure through the oriilce As the mixture of lead globdles and compressed air or gas obtained in passage 2l leaves the oriilce 21, the sudden release and expansion of thehighly compressed air or gas with consequent abrlmt fall in pressure of the mixture ot streams of gas and lead, further divides the lead globules into a dust of exceptional iineness which is deposited in the chamber Il. Because of the spacing of the pencil-like streams of molten metal in the stream of gas in the passage 28, the compressed gas has an opportunity to enter each pencil-like stream of molten metall from all sides thereof and break it up into tine globules, and these globules of molten metal as well as the gas will still remain under a substantial pressure which is approximately that on the passage 2l.

Some slight conception of the disintegrating action of a gas under pressure on a liquid also under pressure may be obtained -by observation of the escape of a mixture of water and air from a domestic water supply faucet, after the water has been turned off at its entrance to a building, such as for replacing washers on..

faucets, and some air admitted to the pipes. Thereafter when the faucet is opened slightly, and pressure restored to the pipes. it will be observed that as either the air or water alone escapes through the cracked or slightly open globules of liquid with a violence which is dependable to some extent upon the pressure under which th'e air or gas was held before its escape through the partially opened va'lve or a restricted orifice. It is believed that this same physical phenomenon 'is responsible for the increased nneness of the powdered metal obtained in accordance with this invention.

In the atomizing or powdering of lead. for example, the lead is preferably heated to a temperature well above its fusion point. which is sufficient to give it a high degree of fluidity because with a decrease in viscosity of the molten metal', the more eil'ectively can the gas or air disintegrate it into finely divided particles. While the fusion point of lead is approximately 625 F., I have found that superior results are obtained when the temperature of the molten f 7 the lead, I have found that the stomping action gasinthe is so rapid that very little oxidation of the disintegrated lead by the heated air results, and the atomized or powdered lead collected in the chamber 38 has a bright silvery-color indicating that but little if any oxidation of the atomized lead has taken place. n

The lead upon standing, however, in contact with air after a considerable interval of time will oxidize slowly and turn black, thus making a surface coating on the'particles of what is familiarly known as black oxide of lead. The relation of the gas pressure on the lead which forces the lead out of the pot in streams into the passage 24, and the pressure of the gas or air delivered to the sleeve 24 for atomizing the lead, is very important if uniform and maximum fineness of the metal or lead is to be obtained. The ratio of the volume of air or atomizing medium to the weight of the metal atomized in a given time is also important. For example, a given minimum volume of air for each pound of metal so atomized must be provided, but this ratio will also depend to some extent upon the relative pressures on the metal and atomizing medium, and upon the particular metal being atomized.

More specifically, when lead has been atomized with compressed air by means of the apparatus shown in Figs. 1 to 4, where the orifice 21 had a diameter of of an inch, air at approximately 80 lbs. per square inch pressure -and at a temperature of approximately 1100 F. atomized molten lead to a powdenof which 98.2% passed through a 200 mesh screen, and the ratio of compressed air to lead employed was approximately 6 cubic feet of compressed air per pound oi' lead sprayed. 'I'he temperature of the lead sprayed was at least approximately 1100 F.

I have found that superior results are obtained when the pressure on the lead in the pot Il is above about 25 pounds per square inch above atmospheric pressure and is preferably at least 30 to 40 pounds per square inch, and the pres-` sure on the air or gas delivered to the sleeve 24 for atomizing or disintegrating the discharged streams or pencils of molten metal is substansingle discharge passage vBil which. like thepassages 33 and I4 of Figs. 2 and 3, also has an outwardly divergent or flaring discharge end BI which directs a diverging pencil or stream of molten lead into the passage 2l directly towards the discharge oriiice 21. 'I'he passage B0 in this example may therefore be disposed approximately centrally of the passage 2l o1' the sleeve 24, and otherwise the construction is the same as described in connection with Figs. l to 4.

'Ihe dimensions of the passages 30,'3I, 33, 34 and 28, and of the orifice 21, and the position of the extension 29 in front of the discharge orifice 21 may advantageously often be varied with the different materials and their viscosities being atomized or sprayed, and may be varied somewhat when one may desire to obtain varying degrees of fineness or uniformity of iineness of the product produced in accordance with this invention. In the atomizing of molten lead, for example, I have obtained excellent results where the passage lll was circular in cross section and approximately :V4 of an inch in diameter, where the passage Il was circular in cross section and approximately of an inch in diameter, where the passages I3 and 34 were circular in cross section and each of approximately i', of an inch tially higher than that on the lead and preferably at least 80 to 100 pounds per square inch above atmospheric pressure. The pressures employed on the lead are suiiicient to overcome the back pressure in the chamber 28 created by said gas. The higher the pressure on the disintegrating gas delivered through the sleeve 24, the greater the explosive or disintegrating effect on the streams of molten metal, but if such pressure is too high in proportion to that on the lead, this pressure will prevent the lead streams from being discharged. The cost of increasing the pressure on the air or gas used to disintegrate the metal increases rapidly with each increase in pressure beyond 10Q pounds per square inch, and the increased iineness of the product so obtained does not always warrant the increased cost. By adjusting the sleeve 24 into and out of the spray casing 2| to various extents, the eiective volume area of passage 2l or the distance'from the dis charge end o f the passages 33 and 34 to the common discharge oriiice 21 may be varied in a manner to obtain the maximum disintegrating eiilciency for the particular operating pressures and for the particular metal being disintegrated.

In the example of the nozzle shown in Fig. 5, instead of a plurality ot small streams being discharged into the passage 24 of the spraying sleeve 24, the extension 29a is provided with but a in diameter, where the passages 33 and 34 were at least an inch long, where the distance from the free end of the extension 29, that is, from the oriiices 35 and 3l, to the discharge orifice 21 was greater than the diameter of the discharge orifice 21 and preferably at least 74 of an inch to an inch, and where the diameter of the passage 24 immediately in front of the discharge oriiice 21 was V4 of an inch. In these examples the air pressure 'on the molten lead in the pot was from 30 to 35 pounds per square inch and in the passage 22 was from 60 to 100 pounds pe;` square inch.

In the example illustrated in Fig. 5 where a single discharge passage 60 for the pencil of lead is utilized, good results have been obtained under the same air pressure, where the passage Ell had a diameter of 54; inch discharging toward a discharge orifice 21 which had a diameter of from 1|; inch to inch diameter, and where the disv charge end of passage Il was from :V4 to 1 inch in front of the discharge orifice 21 and the air pressure the same as above given. Where a plurality of passages such as 32 and 34 are employed, I have found that if they are smaller than inch diameter they have considerable tendency to plug easily, especially where the air or gas pressure delivered to the spraying orifice 21 is at least approximately twice that on the molten lead forcing it out of the pot. I have found that where the distance from the discharge end of the extension 2S to the discharge orifice 21 is 1/2 inch or less, and pressures of at least 30 pounds per square inch on the molten lead and at least double that on the atomizing air, were used, the particles obtained did not have as high a proportion of very ne particles, as where the distance was increased to one inch so as to provide for greater travel of the diverging penci1 of lead into the compressed air, before the two were discharged tvgether through the restricted oriilce 21. The area of the oriiice is greater than that of the lead streams or aggregate areas of the lead streams where a plurality is employed, but not more than nine times the cross-sectional area of said stream or aggregate of streams.` A

While there dimensions and their proportion;

relative to one another may be varied to some extent, they give an approximation of the relative proportions or ratios between them which are preferable in order to obtain the best results. Lead atomized by the apparatus shown in Figs. l to 4, for examplef when tested in a Scott volumeter has an apparent density of about 90 for the run of the material. The superflue component of the atomized lead which is taken from the dust collector through which passes all the air from the chamber Il, has an apparent density or about 50. The run of the product which is collected in the chamber 3l has an unusual uniformity in size. For example, in one average or normal run of atomized lead through this apparatus shown in Figs. 1 to 4, over 95% of the atomized lead falling and being collected in the chamber 3l was fine enough to pass freely through a 200 mesh screen. To put the same result in different terms, the total weight of a sample from an average or sample run, which was collected in the chamber ll, was 186.7 grams. 'I'he portion of that sample that went freely through a 200 mesh screen was 177.7 grams. Of the remainder which did not go through the 200 mesh screen, which was about 9 grams, I found that '1.9 grams would pass freely through a 100 mesh screen, and all the balance went through a 60 mesh screen. This last balance which went through the 60 mesh screen upon examination with a microscope appeared to be in rather flat flakes with .relatively large surface areas which made such nakes easily oxidized.

In another average run or test according to this invention, a bright silvery colored powder was obtained, of which 2.0% was retained on a 100 mesh screen 2.0% was retained on a 150 mesh screen 3.4% was retained on a 200 mesh screen 1.6% was retained on a 250 mesh screen 9.2% was retained on a 325 mesh screen and 81.8% passed readily through the 325 mesh screen.

As explained hereinabove, the stream or streams of lead are discharged into the tubular stream of gas a substantial distance greater than V4 inch away from the spraying orice for the mixture. and this distance is preferably around 3/4 to one inch. If the distance is increased, the molten lead and air will be in contact with one another for a longer period of travel before they are released and sprayed, and because of the fact that the temperature of the lead and air is well above the fusion point of the lead, and for best results. close to the temperature at which the lead tends to form litharge in the presence of air, there would be a tendency to form litharge in the spraying nozzle before the mixture is sprayed, if the time interval for the mixture to travel from the entrance of the lead stream into the air stream tothe spraying orice is too great. By increasing the pressure on both the lead and the air to increase their velocity when meeting one another, and in traveling through the mixing chamber 2l, it is possible to increase the distance of travel of the two streams together before spraying without any serious diiliculty from deposit or building up of litharge on the walls of the mixing chamber. If the temperature is dropped nearer to the fusion point of lead, the lead does not have maximum fluidity. and this increases the diiilculty of getting disintegration of the lead stream into the extremely fine particles.

It will be understood that various changes in u the details and materials, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scopo of the invention, as expressed in the appended claims.

I claim as my invention:

1. In the spraying of fused lead to reduce it to finely divided particles, the improved method Y which comprises passing a tubular stream of a gas having a temperature exceeding approximately 900 F. through a confined chamber and escaping from a substantially restricted, relatively short orifice in a wall of the chamber having an area not more than approximately 1A the maximum cross sectional area of the chamber, under a moving pressure differential in excess of 50 pounds per square inch over atmospheric pressure outside of said chamber, and. simultaneously discharging into the interior of said gas stream in said chamber in a direction generally towards said orice, but at a point spaced from said orifice a distance ranging from about V2 inch to not materially greater than approximately one inch, a stream of molten lead having a cross sectional area less than the area of said orii'lce, a temperature exceeding approximately 900 F., and under a continuous, moving gaseous pressure differential over the atmospheric pressure outside ofsaid chamber in excess of 25 pounds per square inch and suflicient to overcome the back pressure in said chamber created by said gas, whereby said streams will be sprayed together through said restricted orlflce, and the lead will be reduced to finely divided particles before congealing.

2. In the spraying of fused lead to reduce it to finely divided particles, the improved method which comprises passing a tubular stream of a gas having a temperature exceeding approximately 900 F. through a confined chamber and escaping from'a restricted, relatively short substantially restricted orifice in the wall of the chamber having an area not more than approximately V4. the maximum cross sectional area of the chamber, under a moving pressure differential in excess of 50 pounds per square inch over atmospheric pressure outside of said chamber, and simultaneously discharging into the interior of said gas stream in said chamber in a direction generally towards said orifice, but at a point spaced from said orifice a distance ranging from about 1/2 inch to not materially greater than approximately one inch, a plurality of streams of molten lead having an aggregate cross sectional area less than the area of said orifice, a temperature exceeding approximately 900 -F. and under a continuous, moving minimum pressure differential over the atmospheric pressure outside of said chamber in excess of 25 pounds per square inch and sufcient to overcome the back pressure in said chamber created by said gas, whereby said lead streams will be delivered into the gaseous stream in said chamber and then all of the streams sprayed together through said restricted orifice to reduce the lead to finely divided particles before congealing.

3; In the spraying of fused materials to reduce them to finely divided particles, the improved method which comprises passing a tubular stream of a gas through a confined chamber and releas ing it from said chamber through a substantially restricted, relatively short orifice in a wall of the chamber, and under a moving pressure differential over the atmosphere outside of said chambei' in excess ot 50 pounds per square inch, simultaneously discharging into the interior of said gas stream within said chamber, in a direction generally toward said prince but at a point spaced from said oriiice a distance ranging from about n in by said gaseous stream, and raising the temperature of the gaseous stream before it reaches said chamber to approximately the temperature of said materials discharged into said chamber. whereby the material discharged from said oriilce will be in nely divided particles.

4. In the reduction of metallic lead to a iinely divided condition, the improved method which comprises directing a stream oi' molten lead at a temperature of at least approximately 900 F.,

and under a moving pressure differential in excess oi' approximately 25 pounds per square inch over atmospheric pressure. into the interior of a confined tubular stream of the heated gas having a temperature oi at least approximately 900 F. and under a' moving pressure differential in excessoi' 50 pounds per square inch over atmospheric pressure, but not sumcient to create a back pressure on the lead stream suiiicient to stop the flow of said lead stream, and in the same direc'- tion as the direction of traveloi said stream of gas, spraying both streams through a substantially restricted, relatively short spraying orice having an area greater than that or said lead stream, but not more than approximately nine times the cross sectional area oi said lead .stream as it is discharged into v`said gaseous stream, and disposed a distance ranging fromabout y inch to not materially greater than one inch in advance of the junction of the streams and regulating the moving pressure on said streams to discharge in the ratio of approximately 8 cubic feet of gas at 80 pounds per square inch pressure for each pound oi lead sprayed.

. 5. In the` spraying or fused materials to reduce them to a iinely divided condition. the improved apparatus therefor which comprises a casing dening a closed chamber having a relatively short, substantially restricted. vdischarge orince in a wall thereof. a plurality of small conduits opening into said chamber generally towards the said oriilce at a distance ranging from approximately ya inch to not greater than approximately one inch spaced from one another at the points of discharge into said `chamber and having an aggregate total cross' sectional area in said conduits. at approximately the discharge ends thereof, bearing a ratio to the face area oi said oriilce or not less than i to 8, means connecting the chamber of said casing to a heated gas under substantial pressure, means connected to said conduits forsupplying thereto in molten condition the materials to bei subdivided, and means for applying a substantial moving pressure diii'erential to said molten materials for 6. In the spraying of fused materials to reduce them to a iinely divided powder. the improved apparatus which comprises a casing having a substantially restricted discharge oriilce in4 one end thereof. said casing in front ot and towards said orifice at a distance greater than about V2 inch from the oriilce and eccentrically to -said.oriiice, the proportion between the i'ace area oi said oriiice and the aggregate cross sectional areas of said conduits at their discharge ends, being approximately the proportion between two conduits ot approximately oi 9S inch. v

7. In the yreduction of metallic lead to a nnely divided condition, the improved method which comprises directing molten lead in a small streamlike format a temperature o! atleast approxi-v mately 900 F. and under a pressure in excess'oi.

approximately-25 pounds per square inch, and an f a .Y f aggregate cross sectional areav approximately:v`v` equal to the areas oi' two circlesof ,flinchv diameter each, into the interior oi' a confined tubular stream of a heated gas having a tempera;

ture of at least approximately '900 F. and under y a moving gaseous pressure in excess of 50-pounds per square inch over atmospheric pressure. and in the same direction as the direction oi travel of said stream oi' gas. and spraying botliigasA A.

substantially restricted. v short, spraying orince having an area molten lead through a relatively not materially exceeding approximately that of a circle of 1% inch diameter, but greater than the aggregate crosssectional area oi' said molten lead as discharged into said gaseous stream and disposed at a distance of about 55 to about'one inch from the junction oi' the streams. i

8. In the spraying of fused lead to reduce ity to ilnely divided particles. the improved method which comprises discharging a continuous stream of molten lead under gaseous pressure at a texnperature in excess of approximately 900 F. into the interior of a conilned, but substantially larger and tubular stream of ygas of a temperature exceeding approximately 900 F., under substantial pressure at least approximately twice that moving said lead stream but insufficient `to create a backpressure that will stop the ilow of said lead stream, and then spraying a mixture of said streams from a substantially restricted spraying orifice located a distance of about 1/2 to about one inch from the Junction of the streams with an abrupt and substantial fall in pressure on said mixture ofy streams as it passes said orifice. and regulating the ratio of compressed gas and molten lead discharged from said chamber to the pro Y portions of approximately 6 cubic feet oi' gas at spray creating oriilce forcing them through said conduits and into said pounds per` square inch pressurerfor pound of lead sprayed.

9. In the spraying of metallic lead to reduce it to finely divided particles,'the improved meth- -od which comprises introducing a stream ofi' molten lead at a temperature exceeding approx'- imately 900 F. under a gaseous pressure in excess of 25 pounds per square inch into a conilned but larger tubular body of gas having a temperature exceeding approximately 900 F. and under substantial pressure at least twice that on said lead, and then spraying the mixture oi' the molten metal and gas from a substantially restricted in said chamber. spaced inch from the entry of said gas body, larger than each about 1/2 to about one said lead stream into said lead stream but not more than ap'xzoroximate#l 1y nine times the cross sectional `area ot said a plurality of conduits opening into inch diameter and an oriiice* molten lead at a temperature exceeding approximately900 F. under a gaseous pressure in excess of 25 pounds per square inch into a confined tubular but larger body of gas having a temperature exceeding approximately 900 F. and under substantial pressure at least twice that on said lead and then spraying themixture of the molten metaland gas from a materially restricted oriilce in said chamber spaced about 1/2 to about one inch from the entry of said lead stream into said gas body, larger than said lead stream but not more than approximately nine times the cross sectional area of said lead stream, into a space having a substantially lower pressure, whereby phere to said molten material for forcing said molten material through said tube and discharging it into said chamber, and with said gas from said chamber through said orice.

A13. In the spraying of fused metallic lead. to reduce it to a nely divided powder, the improved method which comprises discharging a small stream of said lead in molten condition and at a temperature above approximately 900 F. and under a gaseous pressure in excess of approximately 25 pounds per square inch, into a coniined chamber containing a relatively larger body of a gas having a temperature above approxil which causes the discharge of said stream and the mixture of molten metal and gas, passing said oriflce will undergo an abrupt and substantial fall in pressure, and regulating the ratio of compressed gas and molten lead discharged from` said chamber to the proportions of approximately 6 cubic feet of gas at 80 pounds per square inch pressure for each pound of lead sprayed.

l1. In the spraying of a fused material to reduce it to a finely divided condition, the improved apparatus therefor which comprises a casingdefining a closed chamber having a substantially restricted, relatively short, spray-creating discharge orice in a wall thereof, a tube having a passage opening into said chamber of said casing in a direction generally toward said orifice and at a point spaced from said oriilce about 1/2 to about one inch, the cross sectional area of the passage of said tube at approximately its discharge end having a ratio to the face area of said orice in the range approximately between 1 to 6 and 1 to 9, means connecting said chamber to a source of compressed hot gas, means connecting said tube to a source of said material in moltencondition, and means for applying a gaseous pressure substantially above atmosphere to the body of said molten material to force it through said tube and discharge it into said chamber.

12. In the spraying of fused materials to reduce them to a nely divided condition, the improved apparatus therefor which comprises a casing defining a closed chamber having a relatively short, substantially restricted, spray-creating, discharge orifice in a wall thereof, said orifice having an area not more than approximately 1A of the maximum cross sectional area of said chamber, a tube opening into said chamber and subdivided at its discharge end intoa plurality of small passages opening towards said orifice and adapted to direct streams of a fluid therefrom toward the peripheral zone of the orifice, the aggregate crossv sectional areas of said small passages being less than the area of said orifice, the discharge ends of said small passages being spaced from said orice a distance about 1/2 to about one inch, the length of each of said small passages being greater than a plurality of times its diameter, means connected to said casing anti opening into said chamber for supplying thereto a heated gas under substantial pressure, means connected to the main passage of said tube for supplying thereto in molten condition the material to be subdivided, and means for applying a substantial gaseous pressure greater than atmosinter-mixing of said gas and stream in said chamber,v andthen spraying the mixture of the gas and molten lead from said chamber through a substantially' restricted, relatively short orifice having a face area greater than the cross sectional area of the lead stream discharged into said chamber but not more than approximately nine times such cross sectional area, into a space having a pressure substantially less than that in said chamber, whereby the mixture of lead and gas as it passes said orifice will be subject to an abrupt and substantial fall in pressure.

14. In the reduction of metallic lead to a finely divided condition, the improved method which comprises directing a stream of molten lead at a temperature of at least approximately 900 F. and under a pressure in excess of approximately 25 pounds per square inch, and of across sectional area approximately equal to that of a circle Whose diameter is` approximately s, inch, into the interior of a confined stream of a heated gas having a temperature of at least approximately 900 F. and under a moving gaseous pressure in excess of pounds per square in'ch, and in the same direction as the direction of travel of said stream of gas, and spraying both streams through a restricted, short spraying oriiice having an area approximately equal to that of a circle whose diameter is approximately to inch when the diameter of said lead stream is approximately s, inch.

15. In the-reduction of metallic lead to a iinely divided condition, the improved method which comprises directing molten lead in stream form at a temperature of at least approximately 900 F. and under a pressure in excess of approximately 25 pounds per square inch, and of an aggregate cross sectional area approximately equal to that of a circle whose diameter is at least y?, inch, into the interior of a confined stream of a heated gas having a temperature of at least approximately 900 F. and under a moving gaseous pressure in excess of 60 pounds per square inch, but insufficient to cut oft the flow of lead, and in ,the same direction as the direction of travel of said stream of gas, and spraying both streams through a materially restricted, short spraying orifice spaced more than approximately 1/2 inch from the point of discharge of said lead in stream form into said gaseous stream, and having a face area materially greater than, but not more than nine times the total, aggregate cross sectional areaof the lead as discharged in stream form into the gaseous stream;

16. In the spraying of fused material to reduce it to finely divided particles, the improved method which comprises passing a tubular stream of a gas through a conned tubular chamber and releasing it from said chamber through a substantially restricted. relatively short orifice in a wall thereof and of smaller diameter thanvthe chamber and under a moving pressure diierential over the atmosphere outside of said chamber, in excess of 50 pounds per Square inch, simultaneously discharging into the interior of said gas stream within said chamber, in a direction generally toward said orifice but at a point -spaced from`said orice -a distance ranging from about 1/2 inch to not materially greater than approximately one inch, the molten material in small stream-like form having a cross sectional area less than theV area of said oriilce; and at a temperature well above the fusion point of said material and suillcient to produce approximately maximum iluidity without destruction and injury to the material, and under a continuous moving pressure diil'erential over the atmospheric pressure outside of said chamberin excess of 25 pounds per square inch and suiilcient to overcome the back pressure in said chamber created therein by said gaseous stream and raising the 'temperature of the gaseous stream before it reaches said chamber to approximately the temperature oi said material discharged into said chamber whereby the mateexcess of 25 pounds per square inch at a tem-r which comprises rial discharged from said oriee will be in nely divided particles.

17. In the spraying o! fused lead to reduce it to ilnely divided particles, the improved method discharging a stream otgmolten lead under gaseous pressure in perafturel` in excess oi' approximately 900? F. into the interior ot a conilned, but substantially larger and tubular stream of gas oi' a temperaf ture exceeding approximately 900 F., under substantial pressure at least approximately twice that moving said lead stream but insumcient to Vcreate a back pressure that will stop the flow of said lead stream, and then spraying a mixture o! said streams from a substantially restricted spraying orifice located a distance of about A to about -one inch from the Junction of the streams with an abrupt fail in pressure on said mixture oi.streams as itpasses said orifice, the orifice being smaller in diameter vthanthe air stream but larger in diameter than the lead stream, and regulating the volume of compressed gas and molten lead discharged from said chamber in the ratio of approximately six cubic feet o! gas at il() poundsper square inch pressure for each pound of sprayed lead.

t l v ALLAN W. FERGUSON.

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